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[ Upstream commitfa6f092cc0] The `name` field in `obj->externs` points into the BTF data at initial open time. However, some functions may invalidate this after opening and before loading (e.g. `bpf_map__set_value_size`), which results in pointers into freed memory and undefined behavior. The simplest solution is to simply `strdup` these strings, similar to the `essent_name`, and free them at the same time. In order to test this path, the `global_map_resize` BPF selftest is modified slightly to ensure the presence of an extern, which causes this test to fail prior to the fix. Given there isn't an obvious API or error to test against, I opted to add this to the existing test as an aspect of the resizing feature rather than duplicate the test. Fixes:9d0a23313b("libbpf: Add capability for resizing datasec maps") Signed-off-by: Adin Scannell <amscanne@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20250625050215.2777374-1-amscanne@meta.com Signed-off-by: Sasha Levin <sashal@kernel.org>